1. Field of the Invention
The present invention relates to a shuttle printer which performs line printing by reciprocating a print shuttle equipped with a multiplicity of print heads.
Recently, printers have been demanded to be capable of printing graphic information in addition to characters and of effecting high-speed printing. Therefore, dot printers are widely used. Among them, line printers are effective for high-speed printing. However, it is difficult from the viewpoint of mounting to provide a row of dot print elements for one line horizontally. Dissipation of heat also gives rise to a problem.
Under these circumstances, a shuttle printer has been developed in which a multiplicity of print heads, each having 24 pins, for example, are mounted on a shuttle, and this shuttle is reciprocated through a distance corresponding to an area assigned to each print head, thereby effecting line printing.
2. Description of the Related Art
If such a print shuttle is merely reciprocated to effect printing, vibration is generated in the printer due to momentum of the print shuttle produced according to the mass and velocity thereof. Accordingly, some measure must be taken to prevent generation of such vibration.
In one approach to this problem, a counterweight (balance unit) for canceling the momentum of the print shuttle is connected to it through a link mechanism so that as the print shuttle is reciprocated by a motor, the counterweight moves in linked relation to the reciprocating motion of the print shuttle in a direction reverse to the direction of movement of the print shuttle.
The motion of the counterweight gives counterforce to the momentum of the print shuttle so as to cancel it. Thus, vibration of the printer is prevented.
However, the motor, which is used to drive the print shuttle, must drive not only the print shuttle but also the counterweight together with it through the link mechanism. Accordingly, the load applied to the motor is so heavy that it is difficult to drive the print shuttle at high speed.
If the motor is increased in size in order to effect high-speed driving, the overall size of the printer increases, and the production cost rises.